People with extreme obesity have increased risks of dying at a young age from severe diseases like cancer, heart disease, stroke, diabetes, and kidney and liver diseases, according to results of an analysis of data collected from 20 large studies of people from three countries. In this study it is found that people with class III (or extreme) obesity had a dramatic reduction in life expectancy compared with people of normal weight.
Obesity category is defined on basis of BMI, Below table shows obesity category.
- Normal weight: 18.5-24.9
- Overweight: 25.0- 29.9
- Class I obesity: 30.0-34.9
- Class II obesity: 35.0-39.9
- Class III obesity: 40.0 or higher
The researchers found that the risk of dying overall and from most major health causes rose continuously with increasing BMI within the class III obesity group. Statistical analyses of the pooled data indicated that the excess numbers of deaths in the class III obesity group were mostly due to heart disease, cancer and diabetes.
Years of life lost ranged from 6.5 years for participants with a BMI of 40-44.9 to 13.7 years for a BMI of 55-59.9.